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Can I Sleep In My Car With The AC Running? Safety Tips and Considerations

Sleeping in car with AC running.

Whether you're planning a road trip, waiting for a friend, or want some cool air in your idle car, you've probably pondered the question, "can I sleep in my car with the ac running?"

You should not sleep in your car for extended periods with the AC running. Even though many choose to sit in their car with the AC on, avoid napping for too long with any part of the car running because you could fall victim to carbon monoxide gas, electrical faults, or a drained battery.

Below, we go over everything you need to know about the risks of sleeping in a car with the air conditioner running, whether carbon monoxide comes through the AC, and how to stay safe if you must sleep in your vehicle.

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    Sleeping in car with AC running.
    Sleeping in car with AC running.

    Can I Sleep In My Car With The AC Running?

    Truck drivers and others who drive for a living often nap in their vehicles.

    However, casual drivers may have to take naps while traveling since driving when tired should never be an option.

    That said, sleeping in a vehicle with the air conditioner or engine running is dangerous, so you should always turn climate controls off before getting some shut-eye.

    If left running for extended periods, the AC can risk your car and life.

    How Long Can You Sit In The Car with the Air Conditioning Running?

    Provided your car engine is running and you've got enough gas in the tank, you can leave your AC system on for hours!

    But when your car isn't in motion, and the engine is switched off, you should avoid turning the air conditioner on to prevent draining the battery and carbon monoxide poisoning.

    Can Carbon Monoxide Come From AC in Car?

    Air conditioning systems themselves do not produce carbon monoxide.

    The gas is only emitted through fuel-burning systems.

    However, leaving your AC running while you sleep in your car increases the chances of carbon monoxide infiltrating the cabin and poisoning you.

    Research by the Centers for Disease Control showed that the toxin could become life-threatening in only seven minutes inside a car with the AC running.

    The odorless nature of the gas increases its deadliness as you won't know whether you're inhaling it without a CO detector.

    Can You Sleep In Your Car with the Windows Closed and the Air Conditioner On?

    You shouldn't sleep in your car with the windows closed and the air conditioner on.

    It drastically increases the likelihood of suffering CO poisoning and suffocation from harmful fumes.

    Instead, turn the AC and the car engine off, and crack your windows to give yourself access to the outside air and more oxygen.

    How Cold Is Too Cold to Sleep In Your Car?

    Your car can be a great shelter in times of need.

    However, humans aren't designed to deal with below-freezing temperatures (i.e., anything under 32 Fahrenheit) for prolonged durations.

    If you don't keep warm, you could experience the first stages of hypothermia in as little as ten minutes.

    When the outside temperature drops below freezing, it's best to avoid sleeping in your car.

    That said, you can prepare for winter car sleeping by purchasing thermal clothing (including gloves and socks), insulating your vehicle with reflective foam, and getting a thermal-grade sleeping bag.

    You are at risk of CO2 poisoning sleeping in a car.
    You are at risk of CO2 poisoning sleeping in a car.

    6 Tips to Stay Safe While You Sleep in Your Car

    Sometimes, you'll have no other option but to sleep in your car overnight.

    In these moments, you need to keep the following six tips in mind to sleep safely and avoid harmful exhaust fumes:

    #1 Turn the Engine Off

    Leaving the car running while you sleep exposes you to fumes and could drain your battery and gas.

    Always turn the car's engine off and remove the keys from the ignition before putting your head down.

    #2 Don't Completely Shut the Car Windows

    While you shouldn't leave yourself vulnerable to thieves by leaving your windows rolled all the way down, you should crack them open a slither for ventilation.

    That way, your air intake will remain fresh, but you will maintain safety when parking overnight.

    #3 Park Overnight In a Safe, Legal Place

    Speaking of parking, make sure you find a safe, legal place where cars are permitted overnight.

    Resist simply pulling to the side of the road; find designated rest stops, a parking lot, or other overnight parking solutions, and always check local laws before sleeping in your car.

    #4 Make Sure Someone Knows Where You're Sleeping in Your Car

    At least one person should know where you're safely parked before going to sleep.

    After all, sleeping in a car can never be 100% safe, so protect your life by letting a family member or friend know where you're staying.

    #5 Bring Loads of Blankets

    If you plan to sleep in a car overnight, always bring blankets; it gets colder at night than most people realize.

    That said, a cheap hotel room might be more beneficial.

    You can get away with bringing a portable fan to keep you cool safely while sleeping in your car during the day.


    By now, you should have the answer to your "can I sleep in my car with the ac running" query — and a lot more.

    If you must sleep in your car, always turn the AC and engine off to mitigate the risks of carbon monoxide fatalities, drained batteries, electrical faults, and catching a chill.

    On top of that, always find safe parking zones before getting some much-needed shut-eye.